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TABLE 1 -CHECKLIST OF REQUIRED DATAi�
<br /> FOR NO FURTHER ACTION REQUESTS AT UNDERGROUND TANK SITES
<br /> Site Name and Location: Shawver Trucking,916 Broadway, Stockton, San Joaquin County
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<br />` Y 1. Distance to production wells for municipal, domestic, agriculture, industry 11 Eleven domestic wells are within 2,000 of the
<br />�. and other uses within 2000 feet of the site; it site. The nearest well is located 300 feet north-
<br /> 4 northeast of the former tanks.
<br /> 4 Ii II` In 1999, one 500-gallon gasoline
<br /> 2. Site maps, to scale, of area impacted showing locations of former and existing tank systems, and one 250-gallon waste oil
<br />} excavation co.Ontours and sample locations, boring and monitoring well elevation confours, tank were removed from the
<br /> gradients, and nearby surface waters, buildings, streets, and subsurface utilities; I site.
<br />+ YNo treatment system was used.
<br /> f 3. Figures depicting lithology(cross section), treatment system diagrams;
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<br /> N 4, Stockpiled soil remaining on-site or off-site disposal(quantity); Excavated soil retroed to the tank pit.
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<br /> 5. Monitoring wells remaining on-site, fate; No monitoring wells were installed.
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<br /> 6. Tabulated results of all groundwater elevations and depths to water, Groundwater
<br /> ' Id elevations varied between 50 and 100 feet �
<br /> bgs, with an estimated northeasterly flow di[ection. �
<br /> 7.Tabulated results of all sampling and analyses:
<br /> Elevated levels of TPHd and oil and grease,along with low levels of BTEX were
<br /> detected in sail samples from beneath the waste oil tank. In April 2000,one sof!
<br /> Detection limits for confirmation sampling boring was advanced to 103 feet bgs in the former oil tank pit Sample results
<br /> showed TPHg at 21 mg/kg, TPHmo'at 27,000 mg/kg,and TPHd at
<br /> Lead analyses 3,800 mg/kg in soil samples from 20.5 feet bgs. From 25 to 100.5 feet bgs,soil
<br /> samples were non-detect. Only trace concentrations of toluene,xylene, TPHg,
<br /> and TPHd were detected idwater samples.
<br /> Y� 8. Concentration contours of contaminants found and those remaining in soil,
<br />} and groundwater, andjWth on-site and off-site:
<br /> Lateral and LJ Vertical extent of soil contamination Rh i
<br /> 0 Lateral and 0 Vertical extent of groundwater contaminationFYI 1
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<br /> 9. Zone of influence calculated and assumptions used for subsurface IE No subsurface remediation system was used at
<br /> remediation system and the zone of capture attained for the soil and { thisisite.
<br /> groundwater remediation system;
<br /> FTI 10.Reports/information Y❑ Unauthorized Release Form FN-A-11QMRs(Date's)
<br /> 0 Well and boring logs Y❑ PAR 0 FRP Y❑ Other(report name) Summary Report, Subsurface Invest.
<br /> 11.Best Available Technology(BAT) used or an explanation for not using BAT" The waste oil and gasoline tanks were removed
<br /> h from the site.
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<br /> 12.Reasons why background was/is unattainable using BAT' I i
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<br /> —1 13.Mass balance calculation of substance treated versus that remaining; None submitted.
<br /> 14.Assumptions,parameters, calculations and model used in risk
<br /> assessments, and fate and transport modeling;
<br /> Investigations show that contamination exists in the upper
<br /> 15.Rationale why conditions remaining at site will not adversely 20 feet of soil. Groundwater contamination probably was
<br /> impact water quality, health, or other beneficial uses;and "dragged"from the contaminated soil zone.
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<br /> 16.WET or TCLP results High levels of chromium,zinc,and nickel were detected in soil samples
<br /> during the removal of the waste oil tank.
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<br /> By, Comments: Two tanks were removed in January 1999. During the removal of the waste oil tank,elevated concentrations of TPHd
<br /> and oil and grease were detected in soil samples from the bottom of the tank excavation. In April 2000,one soil boring was installed
<br /> in the location of the former waste oil tank. High levels of TPHg, TPHd,and TPHmo were detected in soil samples from the boring
<br /> Date' at 20 feet bgs. Soil samples from 25 to 100 feet were non-detect for petroleum constituents. Water samples were collected at
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<br /> C? depths of 54 and 103 feet. Trace levels of contaminants only were found in',water samples from 54 feet,.however, these f
<br /> contaminants probabiy were carried down from the contaminated soil zone during the installation of the soil boring,since no
<br /> constituents were found in soil samples below 20 feet. Fuel oxygenates,including MTBE were not detected in samples from the
<br /> site. Eleven domestic water wells are within 2,000 feet of the site, with the nearest well located 300 feet north-northeast. This well
<br /> was installed to 226 feet bgs and screened from 216 to 226 bgs. Based on!the confinement of contamination in the soil zone and
<br /> the absence of MtBE at the site,staff concurs with San Joaquin County's closure recommendation.
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